Using No More Nails to fix a door chain - good idea?

[ReshapeWhileDamp]

We have a balcony out of our bedroom, extending over the dining room extension. Tis very nice out there, giving views to the river. We moved in recently and haven't done anything about the terrible condition of the railings though, which are wooden and rotted through. We have two small DSs and clearly this is a no-go area for them - neither of them have even been out on it with us.

Thing is, the double doors that lead out onto the balcony are the only windows in the bedroom (there is a tiny window in the en-suite that I've been using to ventilate the bedroom until now). We obviously need to open them! DS1 is 3 and will be out there in a flash if the door's left open, and we should also have some security if we want the doors open at night, I suppose (we live in a very low crime area).

I thought a chain like you fit to front doors would work, but the doors are metal-framed and I don't think that drilling them would be a good idea (nor would the screws stay put in a hollow metal doorframe?). So can I glue the chain plates on? They need to be secure enough to withstand a determined small child tugging on the door once he realises what's out there!

Superglue can fail on non-porus surfaces quite suddenly. Is No More Nails any better? I've never used the stuff.

You can drill into metal window frames - I've done it. You should be able to get fixings designed for hollow frames.

I wouldn't rely on No More Nails personally - it works fine for a lot of stuff but I wouldn't trust it if my child's safety were at risk

You can get a locksmith to come along and fix some sort of device that will only allow partial opening.

Actually, have just checked and the whole door unit is UPVC, not metal! So not sure how that changes things. Perhaps we can drill into that and get correct fixings?

Yes you can definitely drill into UPVC (I sound like I drill into a lot of windows :o) - I fitted window locks in my old flat and it was very easy to do.

Ok. That sounds hopeful. Though I'm also tempted by idea of getting a locksmith in...

When you drilled your window frames for locks, did you buy some special fixings for hollow frames - rawlpluggy things?

Use self-tapping screws in UPVC. Drill a hole much smaller than the screw and the screw self-taps (cuts its own thread) as it goes in.